Thermally-assisted recording (TAR), also called heat-assisted magnetic recording (HAMR), has been proposed. In a TAR disk drive, an optical waveguide with a near-field transducer (NFT) directs radiation from a laser to heat localized regions of the magnetic recording layer on the disk. The radiation heats the magnetic material locally to near or above its Curie temperature to lower the coercivity enough for writing to occur by the magnetic field from the write head. The recorded data is read back by a conventional magnetoresistive read head. The optical waveguide, write head and read head are formed on the trailing surface of a head carrier, such as a slider with an air-bearing surface (ABS) that allows the slider to ride on a thin film of air above the surface of the rotating disk.
One of the challenges for TAR is the integration of the laser with the head carrier so that the laser light is directed to the optical waveguide. A vertical-cavity surface-emitting laser (VCSEL) has been proposed because of its high reliability and low cost. TAR sliders with various means for attachment of a VCSEL are described in US 20080002298 A1 and US 20090310459 A1. However, a typical VCSEL does not have adequate power output for currently proposed TAR disk drives.
An extended cavity VCSEL has been proposed where a third mirror is on the back side of the VCSEL semiconductor substrate. The thickness of the semiconductor substrate forms an extended cavity for the VCSEL, which allows for higher single mode power than can be achieved with a typical VCSEL without the external cavity and third mirror. An extended cavity VCSEL is described in U.S. Pat. No. 6,778,582 B1.
What is needed is a TAR head structure with an extended cavity VCSEL integrated with the head carrier.